layer.cornerRadius 不能与 NSLayoutConstraints 结合使用 (swift 3)

Question

以下是我的配置文件视图约束，视图呈现良好，但宽度始终 returns 为零。所以最后的约束，profileImageView.layer.cornerRadius = (profile.frame.width / 2) returns 每次都为零。

    profileImageView.translatesAutoresizingMaskIntoConstraints = false


    addConstraint(NSLayoutConstraint(item: profileImageView, attribute: .width, relatedBy: .equal, toItem: containerView, attribute: .width, multiplier: 0.125, constant: 0))


    addConstraint(NSLayoutConstraint(item: profileImageView, attribute: .height, relatedBy: .equal, toItem: containerView, attribute: .width, multiplier: 0.125, constant: 0))




    addConstraint(NSLayoutConstraint(item: profileImageView, attribute: .centerY, relatedBy: .equal, toItem: containerView, attribute: .centerY, multiplier: 1, constant: 0))

    addConstraint(NSLayoutConstraint(item: profileImageView, attribute: .centerX, relatedBy: .equal, toItem: containerView, attribute: .centerX, multiplier: 0.25, constant: 0))

    profileImageView.layer.cornerRadius = (profileImageView.frame.width / 2)

有什么建议吗？

Answer 1

profileImageView还没有排版，没有尺码。假设这是在 UIViewController 子类中，您可以将圆角半径代码放在 viewDidLayoutSubviews:

中

override func viewDidLayoutSubviews() {
    profileImageView.layer.cornerRadius = (profileImageView.frame.width / 2)
}

Answer 2

profileImageView.frame.width 为零，因为它的帧尚未计算。在你的 profileImageView 重写 layoutSubviews 方法中：

override func layoutSubviews() {
    super.layoutSubviews()
    layer.cornerRadius = bounds.width / 2.0
}

或者，如果您使用的是视图控制器，请覆盖 viewDidLayoutSubviews 方法：

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    profileImageView.layer.cornerRadius = profileImageView.bounds.width / 2.0
}

layer.cornerRadius 不能与 NSLayoutConstraints 结合使用 (swift 3)

layer.cornerRadius not working in conjunction with NSLayoutConstraints (swift 3)

xcode

ios

nslayoutconstraint

swift